1. Field of the Invention
The present invention relates to a transparent electrode provided with stability capable of preventing any degradation due to ion-containing moistures, while being kept acid-proof and alkali-proof.
2. Description of the Related Art
Conventionally, in semiconductor light emitting devices such as LED, and liquid crystal, the electrode is formed, for emitting a light from an electrode side, of a transparent material to allow light to transmit through the transparent electrode and exit it (for example, refer to related art document 1 below). ZnO, which is material as the transparent electrode, is subject to erosion by acid and alkali, and thus may cause loss of a reliability of the electrode under the influence of ion-containing moistures. Moreover, when employed as a white light source utilizing an emission of LED, a semiconductor light emitting device is covered with an epoxy resin mixed with a fluorescent material.
In FIG. 4 there is shown an arrangement of a light emitting device module as a conventional white light source. In FIG. 4, a reference numeral 51 refers to a semiconductor light emitting device, 52 refers to an epoxy resin, 53 refers to a module substrate and 54 refers to moisture. As shown in FIG. 4, the entire semiconductor light emitting devices 51, which is mounted on the module substrate 53 of the light emitting device module, is covered with the epoxy resin 52. The fluorescent material mixed with the epoxy resin 52 is excited by emission from the semiconductor light emitting devices 51 and thus emits white light. However, the moisture is liable to penetrate the epoxy resin 52 so that when any moisture contained inside the epoxy resin 52 or the moisture 54 from the outside penetrates, or in particular, the moisture 54 contains ions, it exhibits acidity or alkalinity, thus, as the case may be, resulting in an erosion of a ZnO transparent electrode employed for the semiconductor light emitting device. It is probably assumed that a high ionization tendency of Zn causes said phenomenon.
[Related Art Document 1]
Japanese patent laid-open publication 11-70610, (FIG. 3, page 3-4)